So what we want to show is that there is no strategy for which the players will win for the 3 challenges received by Bob. What we know from Proposition REF  is that they can't give answers for the 3 challenges simultaneously but this doesn't mean they can't answer each challenge separately. This behavior can appear when we consider entangled strategies. For example in magic square game [1]}, [2]}, Alice and Bob can't answer all questions at the same time — because all the constraints of the magic square game lead to a contradiction. However, the entangled value of the game is still 1.
